1. Field of the Invention
The present invention relates to a cooling tower for performing cooling by using a heat exchanger set to the middle of a water circulation channel, and thereby contacting water with air and releasing the heat of the water.
2. Description of the Prior Art
It is generally known that a refrigerator has been used so far in the fields of chemical processes and air conditioners in order to cool or refrigerate a substance. Moreover, to recycle the water in a condenser of a refrigerator, a cooling tower is normally used. The condenser cools a high-pressure high-temperature refrigerant gas discharged from a compressor of the refrigerator with water to condense (to liquefy) the gas. The cooling water cools the water whose temperature is raised by the condenser by releasing the heat of the water into the atmosphere. The water normally uses industrial water, well water, and city water containing hard components such as calcium, magnesium, and silica ions.
In the case of this cooling tower, as shown in FIG. 4, air 52 outside of a housing 51 is introduced into the housing 51 from an air supply port 54 by the operation of a fan 53. The air 52 passes through a filler 55 and thereafter, it is discharged from an aperture 56 at the top end of the housing 51. Water 57 whose temperature is raised by a condenser 65 of a refrigerator 64 passes through a pipe 66 and a water intake pipe 58 and then, it is sent to a water spray pipe 59 and dripped from the pipe 59. The dripped water 57 slowly flows downward through the filler 55. In this case, the above-described air 52 contacts the water 57 and the heat of the water 57 is released into the air 52. Thus, the temperature of the water 57 is lowered up to 20 to 40.degree. C. due to the release of the heat. The water 57 thus cooled is temporarily stored in a water tank 61 and then, discharged to the outside of the housing after passing through a drain pipe 62. Thereafter, the water 57 is returned to the condenser 65 after passing through the pipe 66.
In the cooling tower 63, the amount of the water 57 flowing through the circulation channel slowly decreases because some of the water 57 in the housing 51 becomes water vapor and goes out of the top-end aperture 56 or the like. Because of the decrease of the amount of the water 57, the concentration of the hard components in the water 57 increases and therefore, the components precipitate and attach to the condenser 65 and the pipe 66 as scales. The scales cause the heat exchange efficiency of the condenser 65 to lower. Moreover, when the water 57 having the high-concentration hard components contacts the condenser 65 and pipe 66, a local potential difference is produced on their contact faces (metallic surfaces). Thereby, a metal fuses at an anode portion and the so-called corrosion occurs. Therefore, it is preferable to prevent the metal from fusing at the anode portion by forming a protective film on metallic surfaces.
Therefore, the so-called blow-down is conventionally performed which forcibly discharges the water 57 to the outside of a circulation channel by opening a drain valve 67 and moreover, the water 57 is renewed by supplying make-up water to the circulation channel to lower the concentration of hard components in the water 57. Moreover, chemicals such as orthophosphate, polymeric orthophosphate, and phosphonate are added to the water 57 so as to form a protective film on the metallic surfaces of the condenser 65 and the pipe 66.
[Problems to Be Solved by the Invention]
In the case of the above conventional cooling tower 63, however, the inside of the housing 51 is released into the atmosphere at the air supply port 54 and the top-end aperture 56. Thus, the sunlight irradiates the inside of the housing 51 through these released portions. Because the cooling tower 63 has a structure of introducing outside air into the housing 51 only by the attraction due to the rotation of the fan 53, it is impossible to close the air supply port 54. Moreover, the cooled water 57 has a temperature (20 to 40.degree. C.) suitable for growth of algae. This temperature is also suitable for breeding of bacteria including Legionella pnuomophila. Therefore, when the cooling tower 63 is used for many years, algae may grow or bacteria may breed at the inside and outside of the housing 51. In this case, it is necessary to remove algae and the like with chemicals. However, a new problem occurs that the circulation channel is clogged with removed algae and the like. This problem cannot be solved as long as algae and the like grow. Thus, the conventional cooling tower 63 is not preferable from the viewpoint of health and moreover, there is a problem that the cooling tower 63 is not suitable for indoor installation.
Furthermore, in the case of the conventional cooling tower 63, it is necessary to decrease the concentration of hard components in the water 57 or add a lot of chemicals to the water 57 as described above and therefore, these operations are troublesome. For this reason, it is considered to soften the hard components by setting a generally-known water softener to the channel of make-up water in the field of boiler systems. However, in the case of the conventional cooling tower 63 in which the air 52 is directly introduced into the housing 51 through the air supply port 54 because it is set to an outdoor well-ventilated place, dust and foreign matter enter the housing 51 together with the air 52 through the air intake port 54 and may be contained in the water 57. Therefore, even when the hard components are softened by the water softener, hard components and impurities are still contained in water and therefore, it is difficult to obtain a satisfactory result.